Oversight board says Giant Mine is putting more waste underground

The Giant Mine Oversight Board – an independent body that monitors remediation of the former gold mine – says it’s concerned about plans to store more contaminated waste underground at the site.

The board, also known as GMOB, is responsible for scrutinizing the federally led remediation project while also devising longer-term solutions for the contamination at Giant, which is on the northwestern edge of Yellowknife.

In its recent annual report, GMOB said the remediation project intends to place new arsenic-contaminated waste in one of the mine’s old underground chambers.

Some 237,000 tonnes of highly toxic arsenic trioxide dust, created while the mine was operating, is already buried underground at the site.

“We think it’s a bad idea. If you want to take a challenge and make it worse or more difficult or complicated, just put it underground,” said Graeme Clinton, chair of the oversight board.

“It’s why we’re in this mess to begin with. We have all this arsenic waste underground and it’s hard to get it out and hard to deal with it, and this just seems to be a poor choice.”

Clinton said one of the oversight board’s main concerns is that the new waste – which is soil from the site that could not be remediated – is very different from the arsenic trioxide dust currently stored beneath the mine.

The oversight board says it has spent years researching the arsenic trioxide dust to better understand it, but doesn’t have the same knowledge of the contaminated soil.

“It’s a concern because the oversight board is responsible for developing a permanent solution for all the contaminants on site, which now includes these new substances in addition to the arsenic trioxide dust,” said Clinton.

He said the remediation project plans to start pumping the waste into Chamber 15, one of the chambers at Giant. Clinton said GMOB is working with the remediation project on a sampling program to study the new waste, but there are concerns over the oversight board’s lack of financial resources to take on the extra research.

The annual report said the oversight board’s annual budget of $300,000 is “extremely small” compared the research costs associated with work to develop a permanent solution for the arsenic trioxide dust.

While GMOB is exploring other funding opportunities, the report asserted the board had “reached the point where critical research opportunities, such as upcycling research, are out of reach with its current research budget.”

Clinton said the oversight board is also worried that three fault lines found in a 1998 geotechnical assessment of Chamber 15 could allow water to flow through the chamber during freshet season.

A spokesperson for GMOB said the board had tried to ascertain whether the remediaton team or Royal Oak Mines, which owned Giant Mine, had implemented recommendations from the 1998 assessment to prevent water from flowing in.

Chamber 15 is within an underground area set up to freeze so the arsenic trioxide dust is locked in place. That means the arsenic-contaminated soil would also be frozen if placed there.

Cabin Radio contacted the remediation project about its plan for Chamber 15. A spokesperson said the project team was reviewing the report and could not speak to “observations” the report made.

“The Project will continue to work with rights holders, stakeholders, and partners to make progress on the concerns identified in the Board’s observations,” the spokesperson said in a May 22 statement.

“The Project team thanks the Giant Mine Oversight Board for their ongoing work and collaboration with the team to ensure the site remains safe for Northerners and the environment throughout the remediation process.”

Before publishing this article, Cabin Radio again contacted the remediation project, which did not respond.

The arsenic-contaminated soil won’t be the first time arsenic waste is stored in Chamber 15. The Mackenzie Valley Land and Water Board was notified on December 18, 2025 that arsenic trioxide waste was placed in the chamber in 2022. According to the notification, the waste was from a historical spill.

Arsenic glass looking positive

In spite of funding constraints, GMOB’s annual report set out “promising” findings in research to develop a permanent solution for the arsenic waste.

“We don’t really want decades and decades of perpetual care,” said Clinton. “We would like to deal with it permanently and as quickly as possible.”

One of the projects that has been successful is incorporating arsenic dust into glass, and Clinton said the glass is ready for cold-weather testing.

In the fall, the Aurora Research Institute and Aurora College will test samples of the arsenic glass to monitor how the glass reacts to rain, snow and northern weather.

“If this glass is stable and it doesn’t leach arsenic and it is an option for a permanent solution, this goes a long way in demonstrating that to the public, such that the public can have greater confidence in it for the future,” said Clinton.

Another research project about which the oversight board is hopeful is a Danish scientist’s work in extracting the pure metallic arsenic out of arsenic waste. The scientist will have a year to determine if his methods will work with the arsenic trioxide dust from Giant Mine.

“What’s most interesting about this particular research is actually finding value in waste,” said Clinton.

“There is an opportunity here to not only stabilize the arsenic trioxide, but to actually physically remove it from site and for it to become a commodity that can be sold.

“If everything were to work out absolutely perfectly, it would go a long way [toward] paying for whatever cost would be associated with the process.”

Not every research project has been successful.

Clinton said after developing “hundreds of recipes” for arsenic cement, “it just didn’t work.” He said the cement blocks with arsenic would often crumble when out of the molds or leach too much arsenic to be safe.

‘Unrealistic’ employment targets

According to the annual report, 2024-25 was “the most intensive year to date” for work on the remediation of the mine site. The annual report said $265 million was spent this past fiscal year compared to $187 million in 2023-24, and 1,966 people were employed in 2024-25.

Even with the increase in work, Indigenous and northern employment has decreased to only 25.5 percent of the remediation project’s total work employment hours.

The remediation project has failed to meet Indigenous and northern employment targets since 2020. The closest it has come to the targets is in 2021, when it reported 45 percent of employment hours were worked by Indigenous and northern employees. The target is 55 to 70 percent.

Clinton said the remediation project is failing to meet its employment targets because they are “unrealistic.”

“Similar to all other industrial projects in the territory who set unrealistic targets for local and Indigenous employment, they’re unable to meet [them] because our labour supply is too small for the size of this project,” he said.

Clinton said other factors make it hard to recruit Indigenous and northern workers, like the seasonal and inconsistent nature of the work, and that people in the NWT lack the skills to do the jobs needed by the remediation project.

“We have major challenges with our labour supply and, in the absence of doing anything truly constructive or transformational about it, then the changes that might come to the territory’s economy in terms of this Arctic infrastructure spending? We will largely just watch it happen,” said Clinton.

What has increased is the remediation project’s Indigenous and northern procurement. The annual report said the remediation project is on track to meet its procurement targets by 2027.

Explaining the difference between what the procurement numbers are showing compared to the employment data, Clinton said procurement targets are an easier target to meet “because [companies] are able to manipulate the market” by using joint ventures with Indigenous businesses.

“There’s this underlying idea that Indigenous procurement will result in greater Indigenous employment and we’re not seeing that, simply because that’s really not how the labour market works,” said Clinton.

Alongside questions about Chamber 15, Cabin Radio asked the remediation project what it is doing to hire Indigenous and northern workers. The remediation project did not respond.